Search results for " Sheep"
showing 10 items of 101 documents
Determination of milk production losses and variations of fat and protein percentages according to different levels of somatic cell count in Valle de…
2018
The somatic cell count (SCC) of milk is widely used to monitor udder health and the milk quality and because of its positive genetic correlation with mastitis this trait was included in breeding schemes of dairy sheep. The aim of this study was to estimate the loss in milk yield (MY) and related composition resulting from different levels of somatic cell count in Valle del Belice dairy sheep. Data were collected between 2006 and 2016 in 15 flocks following an A4 recording scheme. Somatic cell count (SCC), fat and protein percentage (F% and P%) were determined using mid-infrared spectroscopy. To evaluate loss in test day MY, F% and P%, five different classes of SCC were arbitrarily defined: …
Penalized classification for optimal statistical selection of markers from high-throughput genotyping: application in sheep breeds
2018
The identification of individuals’ breed of origin has several practical applications in livestock and is useful in different biological contexts such as conservation genetics, breeding and authentication of animal products. In this paper, penalized multinomial regression was applied to identify the minimum number of single nucleotide polymorphisms (SNPs) from high-throughput genotyping data for individual assignment to dairy sheep breeds reared in Sicily. The combined use of penalized multinomial regression and stability selection reduced the number of SNPs required to 48. A final validation step on an independent population was carried out obtaining 100% correctly classified individuals. …
Genome-wide scan of fat-tail sheep identifies signals of selection for fat deposition and adaptation
2018
Fat tail in sheep represents a valuable energy reserve for facing future climate changes. The identification of genes with a role in the fat-tail phenotype may contribute to understanding the physiology of fat deposition and the mechanisms of adaptation. Genotypic data obtained with the OvineSNP50K array in 13 thin-tail sheep breeds from Italy were used to identify selection signatures of fat tail through pairwise thin- versus fat-tail sheep breed comparisons, with the following fat-tail breeds of the Mediterranean area: two unique Italian fat-tail breeds (Barbaresca and Laticauda), a Barbary sheep breed from Libya, Ossimi breed from Egypt, Cyprus Fat-Tail and Chios from the Greek islands …
A melanocortin 1 receptor (MC1R) gene polymorphism is useful for authentication of Massese sheep dairy products
2011
Massese is an Italian sheep breed, with black or grey coat colour, mainly reared in the Tuscany and Emilia Romagna regions. Recently, the emerging interests in this breed have resulted in the production of Pecorino cheese obtained with only Massese milk. In order to be profitable, this marketing link between Massese breed and its products should be defended against fraudsters who could include milk of other sheep breeds or cow milk in Massese labelled productions. To identify the genetic factors affecting coat colour in sheep, we have recently analysed the melanocortin 1 receptor (MC1R) gene and identified several single nucleotide polymorphisms (SNPs). In this work, as a first step to set …
Sister-chromatid exchange in cultured lymphocytes of ewes and their newborn lambs
1984
The incidence of sister-chromatid exchange (SCE) in cultured lymphocytes of ewes and their newborn lambs was determined using the BrdU-Giemsa technique. In all ewe-lamb pairs, the SCE rate in the lambs was less than that of the ewes. The mean SCE frequencies per chromosome of the ewes after lambing and of the newborn lambs were 0.1909 and 0.1581, respectively. The statistical analysis shows that a significant difference exists between SCE in the adult female sheep and their lambs. At the same time, a negative correlation was observed between SCE rate and cell proliferation. The results of this study are compared with those of previous reports on age-dependency of SCE.
Occurrence of aflatoxins in feedstuff, sheep milk and dairy products in Western Sicily
2003
Samples of feedstuffs (15), milk (40), and cheese (30) coming from sheep and dairy farms (23) or market in WesternSicily were analyzed for their respective content of aflatoxin B1 (AFB1) and M1 (AFM1) to evidence any possible indirectmycotoxin contamination risk to the consumer. Analyses using HPLC and fluorescence detection were performed afterimmunoaffinity column sample extraction and cleanup; AFM1 was detected in 30% of the milk samples at levels rangingfrom 4 to 23 ng/l and in 13% of the cheeses from 21 to 101 ng/kg; in the feed the AFB1 ranged from None of the contaminated samples exceeded the legal limits set down by the European Union for milk (50 ng/l) and feed(5 μg/kg ), or tha…
A Comparative Analysis of Copy Number Variation of the Sheep and Goat Genomes
2010
Recent studies have shown that copy number variants (CNVs) are important sources of variability of mammalian genomes. We applied a cross species array comparative genome hybridization (aCGH) experiment using as reference the cattle genome to investigate, for the first time, variability in the sheep and goat genomes derived from copy number variation and identified 431 and 358 CNVs, respectively. A comparison of these results to those obtained in other mammals for similar experiments is reported. The identified CNVs could be important in determining phenotypic and production differences between and within breeds. Further studies will be carried out to evaluate the identified CNVs from both f…
Evidence for cryptic glacial refugia from North American mountain sheep mitochondrial DNA
2006
The separation of populations by ice sheets into large refugia can account for much of the genetic diversity found in present day populations. The evolutionary implications of small glacial refugia have not been as thoroughly explored. To examine refugial origins of North American mountain sheep Ovis spp., we analyzed a 604 bp portion of the mitochondrial DNA (mtDNA) control region from 223 O. dalli and O. canadensis. Major refugia were identified in eastern Beringia and southern North America, and we found evidence for two smaller refugia situated between the Laurentide and Cordilleran glaciers. Our results are the first to demonstrate support for survival of any organism in the latter two…
Genome-wide diversity of Pagliarola sheep residual population and its conservation implication
2021
Local breeds represent an underestimated resource in terms not only of their important cultural and economical role in marginal areas, but also because they often own a potential genetic pool well adapted to extreme conditions. This fact is of increasing interest, especially when considering climate global challenges where peculiar and uncommon traits could be advantageous. In this study, we genotyped 24 individuals belonging to the small residual Pagliarola sheep population using the OvineSNP50K array, in order to compare its genomic architecture with other 21 Italian local breeds. Moreover, we performed the fixation index (FST) outlier analysis to identify genes most differentiated betwee…
Combined approaches to identify genomic regions involved in phenotypic differentiation between low divergent breeds: Application in Sardinian sheep p…
2019
Selective breeding has led to modifications in the genome of many livestock breeds. In this study, we identified the genomic regions that may explain some of the phenotypic differences between two closely related breeds from Sardinia. A total of 44 animals, 20 Sardinian Ancestral Black (SAB) and 24 Sardinian White (SW), were genotyped using the Illumina Ovine 50K array. A total of 68, 38 and 15 significant markers were identified using the case–control genome-wide association study (GWAS), the Bayesian population differentiation analysis (FST) and the Rsb metric, respectively. Comparisons among the approaches revealed a total of 22 overlapping markers between GWAS and FST and one marker bet…